BedMachine v3: Complete Bed Topography and Ocean Bathymetry Mapping of Greenland From Multibeam Echo Sounding Combined With Mass Conservation.

Greenland's bed topography is a primary control on ice flow, grounding line migration, calving dynamics, and subglacial drainage. Moreover, fjord bathymetry regulates the penetration of warm Atlantic water (AW) that rapidly melts and undercuts Greenland's marine-terminating glaciers. Here we present a new compilation of Greenland bed topography that assimilates seafloor bathymetry and ice thickness data through a mass conservation approach. A new 150 m horizontal resolution bed topography/bathymetric map of Greenland is constructed with seamless transitions at the ice/ocean interface, yielding major improvements over previous data sets, particularly in the marine-terminating sectors of northwest and southeast Greenland. Our map reveals that the total sea level potential of the Greenland ice sheet is 7.42 ± 0.05 m, which is 7 cm greater than previous estimates. Furthermore, it explains recent calving front response of numerous outlet glaciers and reveals new pathways by which AW can access glaciers with marine-based basins, thereby highlighting sectors of Greenland that are most vulnerable to future oceanic forcing.

Disordered animal multilayer reflectors and the localization of light.

Multilayer optical reflectors constructed from 'stacks' of alternating layers of high and low refractive index dielectric materials are present in many animals. For example, stacks of guanine crystals with cytoplasm gaps occur within the skin and scales of fish, and stacks of protein platelets with cytoplasm gaps occur within the iridophores of cephalopods. Common to all these animal multilayer reflectors are different degrees of random variation in the thicknesses of the individual layers in the stack, ranging from highly periodic structures to strongly disordered systems. However, previous discussions of the optical effects of such thickness disorder have been made without quantitative reference to the propagation of light within the reflector. Here, we demonstrate that Anderson localization provides a general theoretical framework to explain the common coherent interference and optical properties of these biological reflectors. Firstly, we illustrate how the localization length enables the spectral properties of the reflections from more weakly disordered 'coloured' and more strongly disordered 'silvery' reflectors to be explained by the same physical process. Secondly, we show how the polarization properties of reflection can be controlled within guanine-cytoplasm reflectors, with an interplay of birefringence and thickness disorder explaining the origin of broadband polarization-insensitive reflectivity.

Reflecting optics in the diverticular eye of a deep-sea barreleye fish (Rhynchohyalus natalensis).

We describe the bi-directed eyes of a mesopelagic teleost fish, Rhynchohyalus natalensis, that possesses an extensive lateral diverticulum to each tubular eye. Each diverticulum contains a mirror that focuses light from the ventro-lateral visual field. This species can thereby visualize both downwelling sunlight and bioluminescence over a wide field of view. Modelling shows that the mirror is very likely to be capable of producing a bright, well focused image. After Dolichopteryx longipes, this is only the second description of an eye in a vertebrate having both reflective and refractive optics. Although superficially similar, the optics of the diverticular eyes of these two species of fish differ in some important respects. Firstly, the reflective crystals in the D. longipes mirror are derived from a tapetum within the retinal pigment epithelium, whereas in R. natalensis they develop from the choroidal argentea. Secondly, in D. longipes the angle of the reflective crystals varies depending on their position within the mirror, forming a Fresnel-type reflector, but in R. natalensis the crystals are orientated almost parallel to the mirror's surface and image formation is dependent on the gross morphology of the diverticular mirror. Two remarkably different developmental solutions have thus evolved in these two closely related species of opisthoproctid teleosts to extend the restricted visual field of a tubular eye and provide a well-focused image with reflective optics.

Non-polarizing broadband multilayer reflectors in fish.

Dielectric multilayer reflectors that are non-polarizing are an important class of optical device and have numerous applications within optical fibres [1], dielectric waveguides [2] and LEDs [3]. Here we report analyses of a biological non-polarizing optical mechanism found in the broadband guanine-cytoplasm "silver" multilayer reflectors of three species of fish. Present in the fish stratum argenteum are two populations of birefringent guanine crystal, each with their optic axes either parallel to the long axis of the crystal or perpendicular to the plane of the crystal. This arrangement neutralizes the polarization of reflection due the different interfacial Brewster's angles of each population. The fish reflective mechanism is distinct from existing non-polarizing mirror designs [4, 5, 6, 7] with the important feature that there is no refractive index contrast between the low index layers in the reflector and the external environment. It is a mechanism that could be readily manufactured and exploited in synthetic optical devices.

Effects of an application of granular carbaryl on nontarget forest floor arthropods.

We evaluated the effects of a single application of granular carbaryl made against nymphal Ixodes scapularis Say on the diversity and abundance of forest arthropods taken in pitfall traps in oak and mixed oak-pine forest sites for 12 wk after treatment in central New Jersey. Significant short-term changes in arthropod assemblages were detected immediately posttreatment. Effects were not distributed equally across taxa. Seasonal changes in numbers and diversity of forest arthropods in the study areas may have affected the impact of the acaricide in the treatment area. Comparison with control areas indicated that reductions in abundance of some arthropod taxa in the treatment area were detectable 12 wk after treatment.

Neutron production from polyethylene and common spacecraft materials.

We report experimental measurements of neutron production from collisions of neutron beams with polyethylene blocks simulating tissue at the Los Alamos National Laboratory Neutron Science Center and 1 GeV/amu iron nuclei with spacecraft shielding materials at the Brookhaven National Laboratory AGS.

A reliability study of measurement techniques to determine static scapular position.

Current shoulder rehabilitation programs encourage scapular stabilization components although, to date, no scientific studies have evaluated changes in scapular position following such rehabilitation. Four different measurement methods of scapular position have been reported in the literature. The purpose of this study was to examine the intratester and intertester reliability of these four methods and to also examine if significant differences exist in scapular position between dominant and nondominant extremities. Thirty-two subjects volunteered for this study. Intraclass correlation coefficients (ICC) revealed acceptable intratester reliability (ICC = 0.81-0.95) for all measurement methods. However, while one method also proved to be acceptable (ICC = 0.91-.92) for intertester measurements, the other three methods were unacceptable (ICC = 0.18-0.69). One tester reported significant differences in scapular position of the dominant and nondominant extremities when using the most reliable method. The second tester found no significant differences with either method. Future research is recommended to reexamine reliability of these methods and measure subjects with shoulder pathology.

A disposable end-tidal CO2 detector to verify endotracheal intubation.

STUDY OBJECTIVE: We compared the performance of the Fenem FEF end-tidal CO2 detector with the TRIMED capnometer to verify endotracheal intubation. DESIGN: The FEF indicates the presence of CO2 by the color change of a chemically treated indicator; the TRIMED uses infrared technology. Both devices were used during 60 intubations. SETTING: Intubations during in-hospital emergency situations outside of the operating room were studied. TYPE OF PARTICIPANTS: Adult patients undergoing intubation for respiratory failure, CPR, and other airway protection situations were enrolled in the study. INTERVENTIONS: The TRIMED monitor and FEF detector were placed in series between the manual resuscitator and the patient's endotracheal tube adapter after endotracheal tube placement. MEASUREMENTS AND MAIN RESULTS: We defined the acceptable criterion for detection of CO2 as production of a positive signal within six manual resuscitator bag breaths. The TRIMED met this criterion in 58 of 60 patients (sensitivity, 0.97) and the FEF met this criterion in 59 of 60 patients (sensitivity, 0.98). A paired t test showed no statistically significant difference in performance between the two devices. In five of nine cases of intubation during CPR, the color change of the FEF was described as "subtle." In one CPR case, a positive signal was not obtained by either device. CONCLUSION: We conclude that the performance of the FEF CO2 detector is equal to that of the TRIMED monitor for verification of endotracheal intubation in nonCPR situations. Interpretation of FEF color changes during CPR should be approached with caution until further studies using the FEF during CPR are completed.

Effective radiation reduction in Space Station and missions beyond the magnetosphere.

Presented are results from a parametric study of the shielding effectiveness of low and high atomic number shields on biological dose equivalent for low-earth-orbit and interplanetary manned missions.